Be careful of comparing speeds of processors.
The 1.67Ghz core duo is probably faster than the 1.73Ghz celeron.
Celeron are VERY slow processors due to lack of on board cache memory which will speed a processor up.
IBM sold their PC business to Lenovo a year or so back and their laptops are no longer badged with IBM but badged with Lenovo.
If it still says IBM then it is a VERY old laptop.
I used to work for IBM and their laptops were always over priced (so they could offer large discounts to big companies) so they were never a great buy for the individuals (although they probably offer large discounts to the university).
I will say one thing though, IBM / Lenovo laptops are generally well built (because they are used by large companies) and they have a great reliability record.
If you prefer the HP go for it. I am sure the IT staff at the uni will be able to configure it for the wireless network, after all you are not going to be the only one taking their own laptop.
If you can find the exact names of the CPUs in the two laptops then you can compare their performance here (and I bet the 1.67Ghz one is faster)
http://www.cpubenchmark.net/